Molding compounds comprising a mixture of block copolymers employed as a modifier for thermosetting unsaturated polyester resin compositions

Abstract

The invention relates to molding compounds modified with a high 1,2 unsaturated carboxylated styrene-butadiene block polymer and a saturated styrene-alpha-olefin block polymer, said molding compounds containing an unsaturated crosslinkable resin, ethylenically unsaturated monomer, filler, reinforcing agent, catalyst, and thickener.

What is claimed is: 
     
       1. A molding compound modifier combination comprising (a) between about 10 and 90% w of a normally solid, carboxy-containing polymer comprising the mixture of structures ##STR5## where P- is a styrene-butadiene block copolymer with the butadiene portion having a microstructure of between about 30 and about 40 mol percent 1,2-vinyl, between about 20 and about 30 mol percent 1,4-cis and between about 30 and about 50 mol percent 1,4-trans and (b) between 90 and 10% w of a block copolymer having the general formula   (A--B).sub.n     wherein A is a block of the group consisting of polystyrene polymer blocks and hydrogenation products thereof having an average molecular weight between about 5,000 and 50,000, B is a polymer block of the group consisting of alpha olefin polymer, conjugated diene polymers, and hydrogenated conjugated diene polymer wherein at least 50% of the original olefinic double bonds have been reduced by hydrogenation said block having average molecular weight between about 10,000 and 1,000,000 and n is an integer between 1 and 25.   
     
     
       2. The modifier combination of claim 1 wherein the weight percentages of structures I, II, III, IV and V in said mixture is about 20 to about 80 percent weight structure I plus II plus III about 10 to about 40 percent weight structure IV and about 10 to about 40 percent weight structure V. 
     
     
       3. The modifier combination of claim 2 wherein the weight average molecular weight of each styrene block in said styrene-butadiene block copolymer is between about 8,000 and about 20,000 and the weight average molecular weight of each butadiene block in said block copolymer is between about 30,000 and about 100,000. 
     
     
       4. The modifier combination of claim 1 wherein the saturated block copolymer comprises isoprene and styrene blocks wherein at least 85% of the original olefinic double bonds have been reduced by hydrogenation. 
     
     
       5. The modifier combination of claim 1 wherein the saturated block copolymer comprises isoprene blocks with molecular weights of between 30,000 and 50,000 and styrene blocks with molecular weights of between 50,000 and 80,000 wherein at least 95% of the olefinic double bonds have been reduced by hydrogenation. 
     
     
       6. The modifier combination of claim 1 wherein at least 99% of the olefinic double bonds have been reduced by hydrogenation. 
     
     
       7. A moldable composition having improved surface smoothness and gloss comprising: (a) an unsaturated, crosslinkable thermosetting resin;   (b) an ethylenically unsaturated monomer;   (c) an additive selected from the group consisting of reinforcing agents, fillers and mixtures thereof; and   (d) a combination of modifiers comprising (a) between about 10 and about 90% w of a normally solid, carboxy-containing polymer comprising the mixture of structures ##STR6## where P-- is a styrene-butadiene block copolymer with the butadiene portion having a microstructure of between about 30 and about 40 mol percent 1,2-vinyl, between about 20 and about 30 mol percent 1,4-cis and between about 30 and about 50 mol percent 1,4-trans and (b) between about 90 and about 10% w of a block copolymer having the general formula   (A-B).sub.n     wherein A is a block of the group consisting of polystyrene polymer blocks and hydrogenation products thereof having an average molecular weight between about 5,000 and 50,000, B is a polymer block of the group consisting of alpha olefin polymer, conjugated diene polymers, and hydrogenated conjugated diene polymer wherein at least 50% of the original olefinic double bonds have been reduced by hydrogenation said block having average molecular weight between about 10,000 and 1,000,000 and n is an integer between 1 and 25.     
     
     
       8. The composition of claim 7 wherein the weight percentages of structures, I, II, III, IV and V in said mixture is about 20 to about 80 percent weight structure I plus II plus III, about 10 to about 40 percent weight structure IV and about 10 to about 40 percent weight structure V. 
     
     
       9. The composition of claim 7 wherein said thermosetting resin is a polyester resin. 
     
     
       10. The composition of claim 9 wherein said polyester resin is prepared by reacting an unsaturated dicarboxylic acid and a polyol. 
     
     
       11. The composition of claim 7 or claim 3 wherein said unsaturated monomer is styrene. 
     
     
       12. The composition of claim 7 wherein said additive is calcium carbonate. 
     
     
       13. The composition of claim 7 wherein said additive is a mixture of calcium carbonate and chopped fiber glass. 
     
     
       14. The composition of claim 7 also containing a catalyst. 
     
     
       15. The composition of claim 14 wherein said catalyst is an organic peroxide. 
     
     
       16. The composition of claim 7 wherein the weight average molecular weight of each styrene block in said block copolymer is between about 8,000 and about 20,000 and the weight average molecular weight of each butadiene block in said block copolymer is between about 30,000 and about 100,000. 
     
     
       17. The composition of claim 7 wherein the saturated block copolymer comprises isoprene and styrene blocks wherein at least 85% of the original olefinic double bonds have been selectively reduced by hydrogenation. 
     
     
       18. The composition of claim 7 where the saturated block copolymer comprises isoprene blocks with molecular weights of between 30,000 and 50,000 and styrene blocks with molecular weights of between 50,000 and 80,000 wherein at least 95% of the olefinic double bonds have been reduced by hydrogenation. 
     
     
       19. A cured article produced by subjecting the composition of claim 14 to heat.